The invention relates to a fuel injection system especially for mixture compressing, externally ignited internal combustion engines in which fuel injection valves inject into the induction tube within which is contained an air flow rate measuring member and a throttle valve, seriatim.
It is the purpose of fuel injection systems of this type to create automatically a favorable fuel-air mixture for all operational conditions of the internal combustion engine so as to produce nearly complete combustion of the fuel and thus to prevent or at least to reduce sharply the generation of toxic components in the exhaust gas while maintaining the highest possible power of the internal combustion engine or the lowest possible fuel consumption.
In known fuel injection systems of this type, the air quantity aspirated by the internal combustion engine is determined by the position of the throttle valve and by the rpm of the engine and a quantity of fuel which corresponds to that aspirated air quantity is supplied by a regulator. These known fuel injection systems have the disadvantage that the metered-out fuel quantity always lags the aspirated air quantity because the air flow rate can be measured only with a certain, finite time delay and fuel can be metered out only thereafter. One of the disadvantages of this delay is the unfavorable transition behavior of the internal combustion engine during a change in the load. For example, when there is a transition from partial load to full load, the fuel air mixture at first becomes leaner because the aspirated air quantity is increased and the desired, corresponding increase of the fuel quantity occurs only after a time delay. On the other hand, during a transition from full load to partial load, the fuel air mixture is at first enriched because the desired reduction of the metered fuel quantity occurs only some finite time after the reduction of the aspirated air quantity.
In the first of these situations, due to the tendency of the fuel-air mixture to become leaner during a transition from partial engine load to full load, the torque of the engine decreases whereas, during a transition from full load to partial load, the torque of the internal combustion engine increases. Yet the desired transition behavior is precisely the opposite of these described conditions, namely increasing torgue during a transition from partial load to full load and decreasing torque during a transition from full to partial load.